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200
METALLURGY 03? IRON AND STEEL.
tion of the exposure. , Thus Table XI-F gives examples of slags produced under abnormal conditions; the samples are from an •open-hearth furnace soon after melting, and before an extreme temperature h'ad been reached to" give the carbon of the bath its Ml reducing power.                                                                        •
TABLE XI-F.
Unstable Basic Open-Hearth Slags.
Slag.	Composition., per cent.			
	BiO...	PaOB.	FeO.	SiOa.+PaOB.
1 2 3 4 5 6 r 8	87.53 84.05 82.45 80.26 25.21 20.60 17.31 15.07	2.01 8.08 8.33 5.99 8.34 10.97 16.60 23.06	10.28 18.45 9.36 10.08 11.88 10.90 12.15 10,58	39.54 87.13 85.78 86.25 83.65 81.57 83.91. 88,13
These slags axe selected as instances of high phosphorus for a given silica, and are, therefore, valueless as an indication of what may be expected in practice.. They show, however, that there is no such thing as a critical percentage of silica, since a cinder with S^t per cent. Si02 may hold 2 per cent. P205. The slags in Table XI-G
TABLE XI-GL Normal Basic Open-Hearth Slags.
Slag.	Composition, per cent.			
	SiOa.	P.O..	FeO'.	SiOa.+PaOB.
1 2 3	20.72-,19.04 12,40	6.36 8.24 18.73	16.20 20.16 . 12.60	27.08 27.28 26.13
are -fairer examples of the: results ^.of regular work. In both Tables XI-F and XI-G there is a-column headed- «SiOa+PjOj/J and the constancy of1 this.total under similar conditions-, even with slags of widely • varying character, indicates that the total acid content of the slag is -the measure of its power to absorb phosphorus: • • '
SEC. Xlk.-—EMminatiort of sulphur.—A certain:'proportion of phosphorus-.is likely to be volatilized by the heat and-carried away in the waste gases.. This renders futile any ^*attempts to make ac^